upon

从前，有一位皇帝非常喜欢衣服。

Once ___upon a time, an emperor liked clothes very much.

从前，有一只鸭妈妈。

Once ___upon a time, there was a mother duck.

从前，一位渔夫在网里捞到了一个瓶子。

Once ___upon a time, a fisherman caught a bottle in his net.